Sum all values in every column of a data.frame in R
RR Problem Overview
Given this data set:
Name Height Weight
1 Mary 65 110
2 John 70 200
3 Jane 64 115
I'd like to sum every qualifier columns (Height and Weight) yielding
199 425
The problem is that the qualifiers can be more than just 2 (i.e. more than just Height and Weight).
I can do this.
# Create the dataframe people
Name <- c("Mary", "John", "Jane")
Height <- c(65,70,64)
Weight <- c(110,200,115)
people <- data.frame(Name, Height, Weight)
res <- c(sum(people$Height),sum(people$Weight))
But it gets too long when the qualifier increase. What's the compact way to do it?
R Solutions
Solution 1 - R
You can use function colSums()
to calculate sum of all values. [,-1]
ensures that first column with names of people is excluded.
colSums(people[,-1])
Height Weight
199 425
Assuming there could be multiple columns that are not numeric, or that your column order is not fixed, a more general approach would be:
colSums(Filter(is.numeric, people))
Solution 2 - R
We can use dplyr
to select only numeric columns and purr
to get sum
for all columns. (can be used to get what ever value for all columns, such as mean, min, max, etc. )
library("dplyr")
library("purrr")
people %>%
select_if(is.numeric) %>%
map_dbl(sum)
Or another easy way by only using dplyr
- As of (dplyr 1.0.0) we can use across()
library("dplyr")
people %>%
summarise(across(where(is.numeric), ~ sum(.x, na.rm = TRUE)))
library("dplyr")
people %>%
summarize_if(is.numeric, sum, na.rm=TRUE)
Solution 3 - R
mapply(sum,people[,-1])
Height Weight
199 425
Solution 4 - R
For the sake of completion:
apply(people[,-1], 2, function(x) sum(x))
#Height Weight
# 199 425
Solution 5 - R
you can also try a <- apply(mtcars[,c(select.colums)], 2, sum )
a <- apply(people[,c(2,3)], 2, sum )